Analysis of the Density of Soil Bacteria Causing Root Rot of Red Kulai Chili (Capsicum annuum L. var. Kulai) and Its Resistance to Various Combinations of Growth Media

This study analyzed the density of soil bacteria that cause root rot of red chili pepper (Capsicum annuum L. var. Kulai) and tested a combination of growth media to improve plant resistance. Contaminated soil samples from organic fields were inoculated into sand and organic soil media, then treated with rice bran and rice water. Isolation of bacteria using the spread plate method resulted in 16 isolates with various morphological characteristics. Biolog Ecoplate™ analysis showed an increase in microbial activity, functional diversity, and community evenness in the combination of rice bran and water. This treatment increased the activity of Azospirillum sp. bacteria that inhibited the pathogen Ralstonia solanacearum while increasing the content of soil micronutrients. The results of statistical tests confirmed a significant increase in microbial activity parameters (p<0.05) and the Shannon-Wiener diversity index. The combination of rice bran and water proved effective in increasing soil resistance to pathogenic bacteria that cause root rot through the mechanism of microbial antagonism and improving soil fertility. These findings offer an organic-based solution for environmentally friendly plant disease control. Keywords: Kulai Chili, Pathogenic, Ralstonia solanacearum, Azospirillum.